Introduction

Local and state emergency managers need a preparedness plan and access to the
best weather information available in order to respond to threatening weather
hazards within their jurisdiction. Experimentation began at FSL in 1992 to
modernize the dissemination of data for local emergency response agencies.
This led to the realization that a decision-making tool akin to a
meteorological forecasting workstation would be very beneficial in helping
emergency managers make better decisions.

In 1997, FSL began building the Local Data Acquisition and Dissemination
(LDAD) system, the community interface and data distribution component of the
Advanced Weather Interactive and Processing System (AWIPS). The LDAD system is
a vital component for automating Weather Forecast Office interactions with
local data observation systems, severe weather spotter networks,
cooperative observers, and local emergency management. Commissioned by
Congress last July, LDAD consists of a configurable local data acquisition
subsystem, a local observation quality control subsystem, and
dissemination via fax, file transfer protocol, bulletin board, and direct
connect for non-Java-capable computers. (The November 1997 issue of the FSL
Forum is dedicated to all of the many topics related to LDAD at that
time.)

The LDAD dissemination strategy includes the Emergency Manager Decision
Support (EMDS) system, a
workstation configuration especially designed to address destructive weather.
It will be installed in every
National Weather Service (NWS) office to provide emergency managers detailed,
easier-to-understand
information (not merely data) that is suited for professionals not formally
trained in meteorology. The EMDS
system (Figure 1) uses graphics, imagery, audio, and text for communicating
important weather information
to those who make crucial weather-related decisions. To accomplish this,
large volumes of a wide variety of
data are accessed in real time and integrated into forecasts that provide more
detail in the mesoscale. The
EMDS system can be used to combine NWS data, Geographic Information System
(GIS) data from local
sources, and protocol from emergency manager situational plans to provide
real-time, concise, and coherent
information to the emergency response community.

Figure 1. An example of information provided by the EMDS system that relates
to the case study used in this
article, the 1997 Fort Collins flood. This screen shows a radar-derived storm
total rainfall of 3–4 inches at
9:05 PM MDT in the Spring Creek drainage area, where the maximum amount of
rainfall occurred.

In this article we use the 1997 Fort Collins, CO, flash flood to demonstrate
the utility of the EMDS as it will
be used in the emergency response community. (An article on the Fort Collins
event is featured in the March
1998 issue of the FSL Forum.)

Complexities of Forecasting Flash Floods

A flash flood often requires particularly complex and difficult decisions on
the part of both the forecasters and
the emergency response community. Unlike most other dangerous weather
phenomena, flash floods are not
simply meteorological events. Accurate NWS forecasts and diagnoses of
rainfall accumulation are not enough
to forecast an event. Flash floods are hydrometeorological phenomena that
involve the complex
interrelationships of rainfall, hydrology, and human activity.

Following a series of particularly disastrous flash floods in the 1970s (Rapid
City, South Dakota, 1972; Big
Thompson Canyon, Colorado, 1976; and Johnstown, Pennsylvania, and Kansas City,
Missouri, 1977), there
was an increase of research toward understanding the scientific processes
responsible for excessive rainfall.
These studies by NOAA scientists represent an important step in understanding
the problem, but they only
address the rainfall aspect of the flash flood phenomenon. Destructive flash
floods have continued to strike
regularly in all areas of the country since the 1970s, but increasingly so in
urban environments. Recent
research at FSL and elsewhere has concentrated more on the nonmeteorological
factors responsible for flash
flooding and the precipitation intensity contribution in hydrologically
sensitive basins.

Although the understanding of excessive rainfall events has improved
significantly since the 1970s, there has
not been a corresponding improvement in the ability to obtain crucial
hydrologic information and to
communicate with other experts on the flash flood problem. Here we want to
illustrate how the EMDS system
is designed to address the communication and hydrological aspects of the flash
flood phenomenon.

Special Features of the EMDS System

The EMDS system facilitates the communication of vital weather and warning
information between agencies
such as the NWS and the local emergency response organizations. This exchange
of information is beneficial
during dangerous flash flood events, especially in view of the rapid and
complex evolution of intense rainfall
and subsequent hydrologic response.

The EMDS system provides real-time radar, satellite, river and basin
information/alerts, moisture and
precipitation related images/overlays, text messages, watches and warnings
through direct communication links
to the emergency response agency, as follows:

Visual and audio tools supplement the traditional text
information to help
emergency responders make more accurate, split-second decisions for dispersal
to the
general public. Before the EMDS system was developed, volatile weather
episodes were
typically described in textual format only. The new system displays
easy-to-interpret color
graphics of weather events that evolve rapidly in both space and time.

Tone alerts have long been utilized to enhance the sense of
urgency with
respect to events such as severe thunderstorm warnings. The animation feature
is used to
monitor every visual aspect of the evolution of the weather event. The
interactive
capabilities are used to probe for specific details and to set alert criteria
based on specific
needs.

Maps tailored to the street configurations of cities
or towns (such as Interstate highways, railroads, rivers, basins, flood
plains, mountain
ranges, land
use, topography, medical facilities, etc.) can be used to complete the
correlation of real-
time data with comprehensive local weather reporting and forecasting.

Text products include routine forecasts and reports, and urgent
messages that
correlate with audio alerts. Alert areas can be graphically viewed by zooming
in on the
entire alert area, county, or zone.

Communication has become less complicated for users of the EMDS
system.
The emergency manager can opt to connect to a reverse 911 system, that is, an
automatic
"phone tree," to notify schools, businesses, or officials at any other
populated place
confronting an impending emergency. This capability can extend to local AM
radio
stations, e-mail, and hand-held pack sets and pagers carried by the emergency
response
staff.

An action protocol is implemented at emergency response agencies
for all
weather information, whether it is benign or leading up to a weather
emergency. The
protocol may relate to a public notice or organizing a special action rescue
team.

Case Study – 1997 Fort Collins Flood

The Fort Collins flood of July 1997 provides an excellent opportunity to study
the various elements that come
together during a flash flood event. This event also provides a comprehensive
look at the various agencies
involved in a weather-related emergency, and how crucial data and information
should be communicated
among these agencies.

On 28 July 1997, Fort Collins was hit by a series of dangerous thunderstorms
that generated 10 inches of
precipitation in 5 1/2 hours. This storm began at approximately 5:30 PM (all
times mentioned are local time,
Mountain Daylight Time) and ended around 11 PM. Roughly half of the total
precipitation fell in the last 90
minutes of the deluge, and it was the most rain ever to fall on a Colorado
urban drainage. This presidentially
declared disaster was the worst in the city's history, with five deaths, over
60 people seriously injured, 2,200
homes or businesses damaged or destroyed, and over $500 million in damage,
marking it as the second most
costly disaster ever to hit Colorado.

On the night of the flood, NWS forecasters contacted county staff to try to
get information on what they knew
to be a deteriorating situation. The NWS was given outlying flood feedback
for the county areas (i.e., rural
areas) but not for the city of Fort Collins. Although the radar provided
spatially accurate precipitation
guidance, unusual tropical conditions led to greater rainfall rates than the
radar guidance could accommodate
(see the 1998 issue of the FSL Forum). The result may have been even more
disastrous except that the weather
forecasters on duty issued a warning anyway, based on experience. In the
hours that followed, firefighters,
police, dive-rescue teams, and private citizens executed 450 rescues, pulling
some victims from certain death
in 8-feet high raging waters.

Emergency Response Possibilities Using EMDS

If the city of Fort Collins had been supported with better and faster
communication links to weather
information, along with additional hydrological data other than radar, earlier
evacuation strategies may have
precluded the need for rapid-water rescues.

The maximum rainfall occurred in the Spring Creek drainage on the southwest
side of Fort Collins. A flood
retention pond just east of this rainfall concentration had passed its maximum
capacity, which caused flooding
in a nearby mobile home park downstream, resulting in the loss of five lives
there. At 9:05 PM, about three
hours into the event, the EMDS radar-derived storm total rainfall indicated
3–4 inches of rain (Figure 1). By
11 PM, 10 inches of rain had actually fallen in the Spring Creek drainage.

Any region can be readily displayed and various parameters can be customized
to distinguish the patterns of
the event. Figure 2 was created using GIS to graphically depict the Fort
Collins watershed, its flood plain, and
streets. This would have provided Fort Collins emergency managers with
immediate access to weather
information tailored to the particular needs of their locale.

Figure 2. A customized EMDS display of the city of Fort Collins shows
streets, watershed, and flood plains.

In this case, by monitoring the real-time radar data updates of the EMDS
system, Fort Collins rescue personnel
could have been kept abreast of the unfolding situation with informational
dispatch tones, while emergency
responders put contingency plans of evacuation into effect. Long before the
EMDS indicated 3–4 inches of
rain at 9:05 PM, traffic could have been diverted from the potential flood
areas, evacuation begun, shelters
prepared, and rescue personnel staged at strategic spots throughout the city.

At roughly 10 PM, the radar-derived storm total rainfall was estimating 5
inches of precipitation over a 12-km2
area. Because of the tropical-like conditions, this was an underestimate.
The final total precipitation was 10
inches, as shown on the isohyetal map (Figure 3). Emergency managers are
trained to plan for the worst.
Even so, three hours into the event (8:30 PM), the Fort Collins emergency
managers began responding to 911
calls, too late for orchestrated evacuations. If the EMDS system had been
available–with its customized
geographical displays and automatic NWS real-time weather updates, emergency
responders would have been
staged in the vicinity of known flood basins and ready to monitor their
situation via hand-held pack sets. At the slightest indication of flooding
(backed-up sewers and flooded basements), evacuation plans could have begun.
This would have been at approximately 7:30 PM, one hour before emergency
personnel responded to 911 calls. Even with the most extreme planning, 10
inches of precipitation probably would not have been expected. However,
evacuation would have been the preferred mode of emergency response, whether 5
or 10 inches of precipitation were predicted. Figure 4 shows two scenes of
one area during and after the Fort Collins flood.

Figure 3. The isohyetal map of rainfall for Fort Collins showing that 10
inches of rain had fallen in the Spring Creek drainage (by 11 PM).

Figure 4. Two scenes from the Fort Collins flood: (above) a rescuer at work
during the flooding of a trailer
park area, and (below) an example of property damage afterward in the same
area.

Summary

Most disasters in this country are weather related and their onset is sudden.
To the emergency manager, however, weather disasters do not just happen
suddenly, they evolve. All weather information, whether insignificant or
leading up to a true emergency, is met with an action protocol (such as
organizing a special action team). Unfortunately, most emergency responders
do not have access to all of the NWS information or forecasts that they need.
Many communities obtain weather information through contract agencies that do
not have the experience and comprehensiveness of the NWS, nor are they aware
of the kinds of services that the NWS can offer them.

The flexible nature of the EMDS system coupled with its capability for
processing volumes of varied data will expedite emergency response to every
weather situation. The simplification of complex weather guidance
or emergency management will result in better services to the public.
Moreover, once the combined technological advances of the EMDS system are
fully implemented, this will dramatically improve the outcome of weather-
related emergencies, subsequently saving lives and money.

[Editor's Note: More information on this project, including bibliographies, is
available at the FSL LDAD Website
]

( Deborah Miller is a Systems
Analyst in the Modernization Division, headed by Dennis Walts. Her contract
affiliation is with System Technology Associates, Inc.)